'Google’s virtual assistant can now make phone calls on your behalf to schedule appointments, make reservations in restaurants and get holiday hours.

The robotic assistant uses a very natural speech pattern that includes hesitations and affirmations such as “er” and “mmm-hmm” so that it is extremely difficult to distinguish from an actual human phone call.

The unsettling feature, which will be available to the public later this year, is enabled by a technology called Google Duplex, which can carry out “real world” tasks on the phone, without the other person realising they are talking to a machine. The assistant refers to the person’s calendar to find a suitable time slot and then notifies the user when an appointment is scheduled.

Google’s CEO, Sundar Pichai, demonstrated the capability on stage at the Shoreline Amphitheater during the company’s annual developer conference, I/O. He played a recording of Google Assistant calling and interacting with someone at a hair salon to make an appointment.

When the salon picks up the phone, a female computer-generated voice says she’s calling to arrange a haircut for “a client” on 3 May. The salon employee says “give me one second”, to which the robot replies “mmm-hmm” – a response that triggered a wave of laughter in the 7,000-strong audience.

“What time are you looking for?” the salon employee asks. “At 12pm,” replies the robot. The salon doesn’t have an opening then, so the robot suggests a window between 10am and 12pm, before confirming the booking and notifying its human master.'